It is known that a heating device of this kind includes a heater having a heating portion which generates heat by energization; a housing which contains the heating portion and forms a passage for a heating medium between the housing and the heating portion; a temperature detection means for detecting the temperature of the heating medium in the passage; and an energization interrupting means for interrupting the carrying of current to the heater depending on the detected temperature of the heating medium.
Patent Document 1 discloses a heating device which is provided with a thermostat or a thermal fuse at the outside of the housing, on a surface shared with the heating face of the heating portion. Thus, the heating device prevents accidental heating of the passage with no heating medium while preventing a malfunction in the thermal fuse.
Patent Document 2 discloses a heating device which is provided with a thermal fuse at the current-carrying terminal. Heat transferred from the heating portion via the current-carrying terminal causes the heating device to interrupt the carrying of current to the heater regardless of the level of the heating medium in the passage so as to prevent accidental heating of an empty passage.
Patent Document 3 discloses a heating device which is provided with a convex on the inside of the housing. The heating device prevents accidental heating of the passage with no heating medium by placing a thermal fuse into contact with the heating portion via the convex of the housing.